Rail braces are utilized to buttress railroad rails against side thrusts exerted by the wheels of rail traffic tending to overturn them. Side thrusts of a magnitude sufficient to overturn a rail most commonly occur at curved sections of the rail which are subjected to high speed rail traffic. When a rail is overturned, the head of the rail is rotated about its origin to a position in which it is offset angularly with respect to a straight line extending from the base through the vertical axis of the rail. The head of a rail rotates with respect to the base of the rail when the lateral forces exerted by rail traffic on the head of the rail are of a sufficient magnitude to overcome the force of the mechanism which anchors the base of the rail to the rail ties. Rotation of the rail head must be prevented at all sections of the rail inasmuch as if a lateral load sufficient to rotate a rail head is applied to the head of a rail over a relatively long length of the rail it is possible that the lateral load could cause the entire rail to roll over and ultimately collapse.
Rail braces are utilized to support a rail and to resist lateral movement of the head of the rail. These braces typically have an upper surface which bears against a fishing surface formed on the underside of the head of the rail and a lower surface which bears against a fishing surface formed on the top side of the base of the rail on the side of the rail opposite that engaged by the flange of a railroad car or locomotive wheel. Traditionally, rail braces have been anchored by being spiked to a wooden tie. However, rail braces anchored in this manner eventually loosen and it becomes necessary periodically to tighten the brace so that it engages firmly the base and head of the rail. Where a brace has been spiked to a railroad tie, it becomes necessary to remove the spikes and redrive them in order to retighten the brace. Eventually, the railroad tie must be replaced because it has been "spiked killed". In order to prevent railroad ties from being spiked killed as a result of removing and replacing spikes to tighten rail braces it has become a common practice to support railroad rails and rail braces on metal brace plates which in turn are anchored to railroad ties.
In addition to the utilization of brace plates it has become common practice to utilize adjustable rail braces which together with the metal brace plates eliminate the need to respite the brace assembly each time a rail brace must be tightened. In one type of adjustable brace, one side of the base of the brace is set at an angle and this side directly engages a stop welded to the brace plate and set at a similar angle to thereby provide a wedging action of the brace between the rail and the stop. In another type of adjustable brace, a wedge is interposed between the rail brace and the stop affixed to the brace plate. In both of these assemblies, the brace must be driven into frictional engagement with the stop or the wedge to firmly secure the rail brace into abutting contact with the rail. After the brace or wedge and brace assemblies have been driven into position, the brace assembly is secured by fasteners such as screws or nuts and bolts. Unfortunately, it has been found that where screws or nuts and bolts are utilized to secure a rail brace assembly to a brace plate, it becomes necessary to inspect periodically the brace assembly to determine if the fasteners have loosened and the braces have moved with respect to the rail. Obviously, when looseness of the brace assembly has been observed, track work maintenance personnel must loosen the fasteners, drive the wedge or brace into engagement with the rail and thereafter resecure the fasteners. Such inspection and tightening of braces by track personnel has increased greatly the cost of maintaining rail lines. Additionally, such maintenance practice necessitates the use of relatively skilled maintenance personnel who must be able to determine the proper degree of tightness for a rail brace.
Because of the time and expense involved in having maintenance personnel inspect and tighten fasteners which secure rail braces to rails, the railroad industry has moved to utilize elastic fasteners such as spring clips to bias rail brace assemblies against stock rails. In one type of adjustable brace assembly utilizing an elastic fastener, one side of the base of the brace is set at an angle with respect to the surfaces on the rail which engage the brace and the angled side of the base engages a stop mounted on a brace plate having a complementary angled face to thereby provide a frictional wedging action for urging the brace against the rail. In this assembly an elastic fastener biases a cover plate downwardly against a flat surface formed on the top of the brace to prevent vertical and horizontal movement of the brace. The surface of the brace may be corrugated and engage a similarly corrugated surface formed on the bottom of the cover plate to further inhibit longitudinal movement of the brace. In this assembly lateral loads applied to the rail brace assembly must be absorbed by a stop affixed to the top surface of a brace plate. Such an assembly may be seen in U.S. Pat. No. 4,566,630.
Another rail brace assembly utilizing an elastic fastener to bias a rail brace assembly into contact with a rail may be seen by referring to U.S. Pat. No. 4,824,015 assigned to the Assignee of the present invention. In this assembly a rail brace is supported on a brace plate and has a downwardly depending lug which becomes trapped within a slot in the brace plate when the rail brace contacts the traffic rail. A resilient fastener biases the rail brace into contact with the track rail. In this assembly rotational and longitudinal forces exerted on the rail brace are absorbed by the lug and brace plate interface whereas lateral forces exerted on the rail brace are counteracted by the elastic fastener.
It has been found that at certain locations in railroad track work and under certain conditions which occur very infrequently, extremely high lateral loads or "spike loads" are applied to brace assemblies from rail traffic. Maximum resistance to these lateral loads is required to properly brace the track rail at these locations. In rare instances, the horizontal component of force may approach the resisting horizontal force component of the resilient fastener.
It has been found that by transferring the lateral component of force exerted on a rail brace assembly to a brace plate that maximum resistance to the lateral load is provided. Transferring the lateral load to the brace plate eliminates the need for welding an auxiliary member such as a stop to the brace plate and adequately resists the very high "spike loads" encountered at certain rail locations.